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Decoupling of a tight‐fit transceiver phased array for human brain imaging at 9.4T: Loop overlapping rediscovered
Author(s) -
Avdievich Nikolai I.,
Giapitzakis IoannisAngelos,
Pfrommer Andreas,
Henning Anke
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26754
Subject(s) - decoupling (probability) , transceiver , phased array , ultra high frequency , physics , computer science , coupling (piping) , resistive touchscreen , topology (electrical circuits) , electronic engineering , acoustics , electrical engineering , telecommunications , cmos , engineering , optoelectronics , antenna (radio) , mechanical engineering , control engineering , computer vision
Purpose To improve the decoupling of a transceiver human head phased array at ultra‐high fields (UHF, ≥ 7T) and to optimize its transmit (Tx) and receive (Rx) performance, a single‐row eight‐element (1 × 8) tight‐fit transceiver overlapped loop array was developed and constructed. Overlapping the loops increases the RF field penetration depth but can compromise decoupling by generating substantial mutual resistance. Methods Based on analytical modeling, we optimized the loop geometry and relative positioning to simultaneously minimize the resistive and inductive coupling and constructed a 9.4T eight‐loop transceiver head phased array decoupled entirely by overlapping loops. Results We demonstrated that both the magnetic and electric coupling between adjacent loops is compensated at the same time by overlapping and nearly perfect decoupling (below ‐30 dB) can be obtained without additional decoupling strategies. Tx‐efficiency and SNR of the overlapped array outperformed that of a common UHF gapped array of similar dimensions. Parallel Rx‐performance was also not compromised due to overlapping the loops. Conclusion As a proof of concept we developed and constructed a 9.4T (400 MHz) overlapped transceiver head array based on results of the analytical modeling. We demonstrated that at UHF overlapping loops not only provides excellent decoupling but also improves both Tx‐ and Rx‐performance. Magn Reson Med 79:1200–1211, 2018. © 2017 International Society for Magnetic Resonance in Medicine.